LSU BIOL 2051 Exam #1 - Bhattacharyya Louisiana State
University and Agricultural & Mechanical College
Questions with 100% Verified Answers Latest Update
Question: what are Koch's Postulates?
Answer:
a set of four criteria developed by Robert Koch in the late 1800s to establish a causal
relationship between a specific microorganism and a disease.
1. the microorganisms must be present in every case of the disease but absent from
healthy individuals
2. the suspected microorganisms must be isolated and grown in pure culture
3. the same disease must result when the isolated microorganism is inoculated in a healthy
host
4. the same microorganism must be isolated again from the diseased host
Question: why was the discovery of phagocytic cells in the blood important?
Answer:
Phagocytic cells are a type of immune cell that protect the body by engulfing (eating),
digesting, and destroying pathogens, dead cells, and debris.
foundational discovery for CELL-MEDIATED IMMUNITY
Question:
Answer:
Question: why does the field of microbiology include macroscopic organisms like algae and
fungi?
Answer:
their study requires techniques like isolation, sterilization, and culturing
Question: what is scanning electron microscope (SEM) used for?
Answer:
observing a specimen's three dimensional topography (physical features of a surface or
region)
Question: what limitation does heat fixing a bacterial smear have?
Answer:
distorts internal stuctures (sacrifices accuracy of cell size/shape and prevents study of live
cells)
Question: what is the primary stain used in gram staining procedures?
, Answer:
crystal violet
Question: what is the purpose of applying a counterstain in a differential staining
procedure?
Answer:
adds a visible color to the decolorized cells
Question: what is the purpose of using mordant in flagella staining?
Answer:
modordant- makes the primary stain stick better and show up more clearly.
increases the diameter of the flagella to make them visible
Question: what is the term for bending light as it passes from one medium to another?
Answer:
refraction
Question: what was the feature of Pasteur's swan neck flasks that prevented contamination
of the sterile broth?
Answer:
Pasteur's swan-neck flask experiment is one of the most famous demonstrations in
microbiology, designed by Louis Pasteur in the 1860s to disprove spontaneous generation
(the idea that life could arise from nonliving matter).
How it worked: Nutrient broth was boiled inside a flask with a long, curved "swan-neck" tube
to sterilize it. The curved neck allowed air to enter but trapped dust and microorganisms in
the bend, preventing them from reaching the broth. Because no microbes reached the
broth, it remained clear and free of growth for months. If the flask neck was broken off or
the flask tipped (allowing broth to contact the dust in the bend), microbes quickly grew. Key
conclusion: Microbes come from other microbes, not from spontaneous generation. Air itself
did not create life; it only carried microorganisms.
long curved neck trapped airborne microbes and dust
Question: what microscope has a resolution powerful enough to observe individual atoms?
Answer:
scanning tunneling electron microscope
Question: which microscope is suited for observing intracellular structures by enhancing
contrast in living cells that have slight differences in refractive index?
Answer:
,phase-contrast microscope
Question: which staining technique is used to visualize bacterial capsules?
Answer:
negative staining
Question: which type of microscope produces a bright image of an object against a dark
background and is ideal for observing living unstained specimens?
Answer:
dark field microscope
Question: which type of microscope uses a beam of electrons passing through a thin section
of specimen to create an image of its internal structures?
Answer:
transmission electron microscope (TEM)
Question: who demonstrated that dust is a carrier of microbes and also provided evidence
for heat resistant bacteria?
Answer:
john tyndall
Question: who developed antiseptic surgical techniques to prevent wound infection and
indirect evidence for germ theory of disease?
Answer:
joseph lister
Question: who was the first person to observe and describe microorganisms using his own
microscope?
Answer:
antony van leeuwenhoek
Question: what type of light does a fluorescence microscope require the specimen be
exposed to excite its fluorophores?
Answer:
ultraviolet, violet, or blue light
Question: what genus of bacteria is identified using acid fast staining as a differential
procedure?
, Answer:
mycobacterium
Question: what vaccination did Edward Jenner pioneer that uses material from cowpox
lesions?
Answer:
smallpox
Observation: Jenner noticed that milkmaids who had contracted cowpox (a mild disease) did
not get smallpox, a deadly disease. Experiment (1796): He took pus from a cowpox sore on
a milkmaid’s hand and inoculated an 8-year-old boy, James Phipps. The boy developed mild
cowpox symptoms but did not get sick when later exposed to smallpox. Impact: Jenner’s
work demonstrated that exposure to a related, less dangerous pathogen could protect
against a deadly disease. This was the first scientific demonstration of vaccination (“vacca”
= cow in Latin). Legacy: Smallpox was eventually eradicated worldwide thanks to
vaccination programs inspired by Jenner’s work. He is remembered for pioneering the idea
of preventive immunization, saving millions of lives.
Question: what is the function of iodine in gram staining?
Answer:
serves as a mordant, forming an insoluble complex with the primary stain
modordant- makes the primary stain stick better and show up more clearly.
insoluble complex -chemical compound formed when two or more substances combine and
produce a solid that does not dissolve in water or another solvent
Question: what vaccines did Pasteur develop?
Answer:
anthrax, rabies, and chicken cholera
Pasteur’s vaccines were based on attenuation, weakening the pathogen so it could
stimulate immunity without causing full disease.
Question: what is microscope resolution?
Answer:
the ability of the microscope lens to distinguish between two small objects that are close
together
Question: what is the atomic force microscope used for?
Answer:
viewing surfaces that do not conduct electricity well
Question: what is the outcome of the gram stain procedure?
University and Agricultural & Mechanical College
Questions with 100% Verified Answers Latest Update
Question: what are Koch's Postulates?
Answer:
a set of four criteria developed by Robert Koch in the late 1800s to establish a causal
relationship between a specific microorganism and a disease.
1. the microorganisms must be present in every case of the disease but absent from
healthy individuals
2. the suspected microorganisms must be isolated and grown in pure culture
3. the same disease must result when the isolated microorganism is inoculated in a healthy
host
4. the same microorganism must be isolated again from the diseased host
Question: why was the discovery of phagocytic cells in the blood important?
Answer:
Phagocytic cells are a type of immune cell that protect the body by engulfing (eating),
digesting, and destroying pathogens, dead cells, and debris.
foundational discovery for CELL-MEDIATED IMMUNITY
Question:
Answer:
Question: why does the field of microbiology include macroscopic organisms like algae and
fungi?
Answer:
their study requires techniques like isolation, sterilization, and culturing
Question: what is scanning electron microscope (SEM) used for?
Answer:
observing a specimen's three dimensional topography (physical features of a surface or
region)
Question: what limitation does heat fixing a bacterial smear have?
Answer:
distorts internal stuctures (sacrifices accuracy of cell size/shape and prevents study of live
cells)
Question: what is the primary stain used in gram staining procedures?
, Answer:
crystal violet
Question: what is the purpose of applying a counterstain in a differential staining
procedure?
Answer:
adds a visible color to the decolorized cells
Question: what is the purpose of using mordant in flagella staining?
Answer:
modordant- makes the primary stain stick better and show up more clearly.
increases the diameter of the flagella to make them visible
Question: what is the term for bending light as it passes from one medium to another?
Answer:
refraction
Question: what was the feature of Pasteur's swan neck flasks that prevented contamination
of the sterile broth?
Answer:
Pasteur's swan-neck flask experiment is one of the most famous demonstrations in
microbiology, designed by Louis Pasteur in the 1860s to disprove spontaneous generation
(the idea that life could arise from nonliving matter).
How it worked: Nutrient broth was boiled inside a flask with a long, curved "swan-neck" tube
to sterilize it. The curved neck allowed air to enter but trapped dust and microorganisms in
the bend, preventing them from reaching the broth. Because no microbes reached the
broth, it remained clear and free of growth for months. If the flask neck was broken off or
the flask tipped (allowing broth to contact the dust in the bend), microbes quickly grew. Key
conclusion: Microbes come from other microbes, not from spontaneous generation. Air itself
did not create life; it only carried microorganisms.
long curved neck trapped airborne microbes and dust
Question: what microscope has a resolution powerful enough to observe individual atoms?
Answer:
scanning tunneling electron microscope
Question: which microscope is suited for observing intracellular structures by enhancing
contrast in living cells that have slight differences in refractive index?
Answer:
,phase-contrast microscope
Question: which staining technique is used to visualize bacterial capsules?
Answer:
negative staining
Question: which type of microscope produces a bright image of an object against a dark
background and is ideal for observing living unstained specimens?
Answer:
dark field microscope
Question: which type of microscope uses a beam of electrons passing through a thin section
of specimen to create an image of its internal structures?
Answer:
transmission electron microscope (TEM)
Question: who demonstrated that dust is a carrier of microbes and also provided evidence
for heat resistant bacteria?
Answer:
john tyndall
Question: who developed antiseptic surgical techniques to prevent wound infection and
indirect evidence for germ theory of disease?
Answer:
joseph lister
Question: who was the first person to observe and describe microorganisms using his own
microscope?
Answer:
antony van leeuwenhoek
Question: what type of light does a fluorescence microscope require the specimen be
exposed to excite its fluorophores?
Answer:
ultraviolet, violet, or blue light
Question: what genus of bacteria is identified using acid fast staining as a differential
procedure?
, Answer:
mycobacterium
Question: what vaccination did Edward Jenner pioneer that uses material from cowpox
lesions?
Answer:
smallpox
Observation: Jenner noticed that milkmaids who had contracted cowpox (a mild disease) did
not get smallpox, a deadly disease. Experiment (1796): He took pus from a cowpox sore on
a milkmaid’s hand and inoculated an 8-year-old boy, James Phipps. The boy developed mild
cowpox symptoms but did not get sick when later exposed to smallpox. Impact: Jenner’s
work demonstrated that exposure to a related, less dangerous pathogen could protect
against a deadly disease. This was the first scientific demonstration of vaccination (“vacca”
= cow in Latin). Legacy: Smallpox was eventually eradicated worldwide thanks to
vaccination programs inspired by Jenner’s work. He is remembered for pioneering the idea
of preventive immunization, saving millions of lives.
Question: what is the function of iodine in gram staining?
Answer:
serves as a mordant, forming an insoluble complex with the primary stain
modordant- makes the primary stain stick better and show up more clearly.
insoluble complex -chemical compound formed when two or more substances combine and
produce a solid that does not dissolve in water or another solvent
Question: what vaccines did Pasteur develop?
Answer:
anthrax, rabies, and chicken cholera
Pasteur’s vaccines were based on attenuation, weakening the pathogen so it could
stimulate immunity without causing full disease.
Question: what is microscope resolution?
Answer:
the ability of the microscope lens to distinguish between two small objects that are close
together
Question: what is the atomic force microscope used for?
Answer:
viewing surfaces that do not conduct electricity well
Question: what is the outcome of the gram stain procedure?
